Is there any reason not to always use the second on position (camera and quick control dial operate) rather than the on position (camera operate) when shooting? If I use the second position, and set custom function C.Fn 13 to 2, I can select AF points directly with quick control dial and also change exposure compensation by holding down the select AF points button while turning the main dial. This only works in second on position, not the on position. Why did Canon put both positions on the camera?